1. Technical Field
The present invention relates to an ink-jet recording method which gives excellent coloring property, ink drying property, and scratch resistance when printing is carried out with an ink-jet printer using glycol ink.
2. Background Art
In recent years, according to rapid innovation of ink-jet recording techniques, extremely excellent quality, which surpasses image quality obtained in silver-salt photography, can be obtained in an ink-jet printer. Thus, the ink-jet printer has rapidly spread as a printer for office use or home use. Also, the ink-jet printer has rapidly spread in the field of sign and displays such as indoor and outdoor advertisement.
Ink to be used for an ink-jet printer are roughly classified into dye ink and pigment ink. When the dye ink is used, excellent coloring property can be obtained whereas there are demerits that water resistance and weather resistance are inferior. On the other hand, when the pigment ink is used, excellent water resistance and weather resistance can be obtained, but there is a demerit that coloring property is inferior to that of the dye ink. However, due to improvement in pigment-dispersing techniques in recent years, excellent coloring properties which are equal to those of dye ink can be realized. Therefore, as the ink used for an ink-jet printer, it is a recent trend to gradually shift from dye ink to pigment ink.
Also, pigment ink used for an ink-jet printer are roughly classified into an aqueous-type pigment ink and a solvent-type pigment ink.
The aqueous-type pigment ink mainly contains water as a dispersant for a pigment, and therefore that has a little less odor, but a density of the pigment cannot be made dense whereby there have defects of being inferior in printing density and sharpness of colors.
On the other hand, the solvent-type pigment ink is an ink which comprises a pigment dispersed in a solvent mainly comprising cyclohexanone or methyl ethyl ketone, and is excellent in high density and color sharpness. Also, the ink itself has excellent water resistance, so that it has spread in the field of an announcement, an advertisement, etc. It has, however, strong odor which greatly affects on a working environment of operators to handle the materials. Therefore, the operators are required to be a specific licensee for handling an organic solvent, and a special ventilation duct is also required to be provided.
As a method to solve these problems, an ink-jet system using oily ink has been proposed. The oily ink is an ink in which an oil-soluble dye, an organic pigment, an inorganic pigment, etc. is/are dissolved or dispersed in a solvent such as a paraffin, an ether, an alcohol, etc. When an image is recorded on an ink-receptive layer by using the oily ink, however, drying property of a solvent remained in the ink-receptive layer is poor so that it is required to dry the material for a long period of time. Therefore, it involves a problem that working efficiency is markedly lowered.
Thus, glycol ink in which a pigment is dispersed in a solvent mainly comprising a glycol ether has been developed. Specifically, it comprises polyoxyethylene glycol dialkyl ether, polyoxyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, etc. as a primary solvent, and contains 60 parts by weight or more of a glycol ether based on 100 parts by weight of the ink. This ink is a solvent-type pigment ink as newly developed. The glycol ink has less smell and is excellent in water resistance, as well as in this ink, defects of the conventional solvent ink have been resolved. Also, it has a merit that an evaporation rate of a solvent remained in an ink-receptive layer after recording is faster than that of the oily ink. In recent years, the glycol ink is spreading, but it involves a problem that the printed area is easily peeled off when that area is rubbed as compared with the conventional solvent-type ink. Thus, an ink-jet recording material suitable for glycol ink has been required.
As an ink-jet recording material to be used in an ink-jet recording method, two kinds of materials have generally been used. The one is a swelling type which generally comprises a resin absorbing a solvent in ink as a main constitutional component, and the other is a microporous type which comprises pigment particles and a resin as main constitutional components, and absorbs ink by voids in an ink-receptive layer having porous structure thereof.
As a recording material in which a microporous type ink-receptive layer is provided, it has been disclosed an ink-jet recording material in which a porous structural ink-receptive layer comprising silica particles and a water-soluble resin is provided on a substrate (for example, see Patent Literature 1). This recording material has excellent ink drying property, but this is a recording material designed for an aqueous ink, so that when a solvent ink, in particular, a glycol ink is used, scratch resistance after printing cannot be obtained. Therefore, it involves a fatal defect that the image is missed when the printed area is erroneously rubbed. Also, it has been disclosed an ink-jet recording material in which an ink-receptive layer having a porous structure and comprising particles and a non-water-soluble resin as main constitutional components has been provided (for example, see Patent Literatures 2 to 6). In these recording materials, the resin component(s) to be used is/are contained in an excessive amount to those of the particles and a porous structure with a higher void ratio cannot be realized, so that a long period of time is required for a drying procedure whereby a working efficiency is markedly lowered. Moreover, there have been disclosed an ink-jet recording material (for example, see Patent Literature 7) which comprises a porous layer containing water-insoluble organic particles as a front surface layer, or an ink-jet recording material (for example, see Patent Literature 8) which comprises a support and a gloss-appearing layer having a solvent absorbing property thereon, and contains a polymer soluble in an isoparaffin type hydrocarbon. However, these materials do not intend to solve the problems involved in an ink-jet recording system using the glycol ink which is an object of the present invention.
As a recording material in which a swelling type ink-receptive layer is provided, it has been disclosed an ink-jet recording material (for example, see Patent Literature 9) which employs a vinyl chloride-vinyl acetate copolymer as a resin capable of swelling or being dissolved in a solvent for ink, or an ink-jet recording material (for example, see Patent Literature 10) having an ink-receptive layer which mainly comprises an acrylic-type resin. When drying is sufficiently carried out after printing, these materials have excellent scratch resistance. However, drying for a long period of time is required since they are inferior in ink absorption property, and they cannot be preserved by laying the printed material on the other ones when a large number of materials are printed out so that working efficiency is remarkably lowered.    Patent Literature 1: JP 2000-238422A    Patent Literature 2: JP 2004-322552A    Patent Literature 3: JP 2004-330465A    Patent Literature 4: JP 2004-50509A    Patent Literature 5: JP 2000-335084A    Patent Literature 6: JP 2000-335082A    Patent Literature 7: JP 2003-200649A    Patent Literature 8: JP Hei. 10-250218A    Patent Literature 9: JP 2004-106190A    Patent Literature 10: JP 2004-291561A